If he's not able to also provide them with a sizeable initial capital, this lesson is also completely irrelevant. No one becomes really wealthy by investing savings off their modest salary.

I mean you can literally do that. And get wealthly. It'll just be a meagre existence up and until retirement.

You can, however, get wealthy by investing savings off a good salary.

It's better to invest in assets though than just the stock market. The wealthy build wealth by borrowing and buying assets like real estate. This ways makes it easier to avoid income taxes and capital gains taxes and you also get massive tax deductions for asset deprecation that you can use to offset most or all of what income it does provide.